Check Polarity of Thermocouples and Lead Wires

Standard Practice at L&L

The following is the standard practice describing thermocouple polarity for Type K and Type S thermocouples that is used on L&L kilns.

Testing polarity of a Type K thermocouple

You can easily test the polarity of a Type K thermocouples. The negative wire is MORE magnetic than the positive wire. Just put a magnet up to each wire. One will be more magnetic than the other. (This does not work for Type S thermocouples.)